TUB 



GEOLOGICAL MAOAZINE. 



No. CVI.— APRIL, 1873. 



L — On Halonia of Lindley and Hutton and Ctclocladia of 



GOLDENBERG. 

 By "William Caerutheks, F.R.S., 

 Of the British Museum. 

 (PLATE VII.) 

 f pHE genus Halonia was established in the Fossil Flora (vol. ii., 

 _1. p. 13) by Lindley and Hutton for those fossils in which, to the 

 surface of Lepidodendron, is added the mode of branching of certain 

 ConifercB, and which were therefore inferred to be of a nature 

 analogous to the latter. It was assumed that Lepidodendron, being 

 an extinct form of Lycopodiacece, must be limited to the fossils in 

 which the branching was dichotomous, since no other kind of 

 branching is met with in recent Lycopodiacece. But when we look 

 at such plants as Lycopodium cernmim and L. densum, we find 

 branching precisely similar to that in Halonia gracilis, L. and H. ; 

 and whether these were produced or not by the division of a termi- 

 nal bud, it is certain that in their developed condition they are 

 arranged in an alternate manner round a common elongated axis — 

 a plan of branching characteristic, as the authors of the Fossil Flora 

 supposed, of Coniferce. 



Whether this plant be Lycopodiaceous or Coniferous however, 

 the genus was accepted, and has been retained by subsequent 

 systematists. Lindley and Hutton figured a second species, to which 

 they gave the name H. regularis (I.e. plate 228) ; and a third fossil 

 they referred with doubt to the same genus, H. ? tortuosa (I.e. plate 

 85). In the description of the latter fossil many conjectures are 

 thrown out, but no accepted interpretation is adopted. 



Brongniart, in the unfortunately incomplete second volume of his 

 " Histoire des Vegetaux Fossiles," (1837) figures (plate xxviii., fig. 2) 

 a characteristic specimen, on a portion of which the film of coal 

 remains, with indications of the leaf-impressions. The letter-press 

 to this plate was never published. The genus is shortly described 

 by Brongniart in his "Tableau," (1847), and the tubercles which 

 distinguish it are described as being covered uniformly with the 

 common bark and the leaves which spring from it, and are considered 

 by him to be like what would be produced by roots which had not 

 passed through the bark. 



Mr. Dawes, in a short paper communicated to the Geological 

 Society in 1848, described the internal structure of Halonia. He 



VOL. X. — NO. cvi. 10 



